Intake apparatus for internal combustion engine

ABSTRACT

An intake apparatus for an internal combustion engine comprises an intake manifold ( 1 ); a rotary valve ( 10 ) including a plurality of valve portions ( 11 ) in communication with air feeding passages ( 3 ) through feed switch openings ( 7 ); a sealing member ( 60 ) fitted to the valve portion, the sealing member including ring portions ( 61 ) and interconnecting portions interconnecting the ring portions, recessed portions ( 76 ) defined on an outer side of the valve portions for receiving engaging portions ( 64 ) on inner sides of the interconnecting portions of the sealing members, wherein a distance (D 1   a ) from a central portion of an outer peripheral edge ( 20   a ) of the closed area portion ( 20 ) to the rotational axis (P) is set smaller than a distance (D 2 ) from a second central portion ( 43 ) of an outer peripheral edge ( 40   a ) of the open area portion ( 40 ) to the rotational axis.

TECHNICAL FIELD

The present invention is directed to an intake apparatus for an internalcombustion engine.

BACKGROUND ART

An intake apparatus for an internal combustion engine is known from e.g.U.S. Pat. No. 6,138,628.

The intake apparatus for an internal combustion engine disclosed in thispatent comprises an intake manifold and a camshaft controller disposedwithin this intake manifold.

The intake manifold forms a plurality of air feeding passages withindividual induction tubes and shorter individual induction tubes forrespectively feeding air to a plurality of cylinders of the internalcombustion engine.

The camshaft controller includes a plurality of portions that haveopenings and that are rotatable together. Each portion is operable toopen and close an individual induction tube associated therewith.

Each portion of the camshaft controller includes a sealing cage. Thissealing cage includes a pair of ring elements and sealing barsconnecting the pair of ring elements to each other. Each ring element isfitted within a groove located at a corresponding end of the valveportion.

This type of intake apparatus has an arrangement whose general principleis illustrated in FIGS. 14( a) and 14(b). It is to be understood thatFIGS. 14( a), 14(b) and the description here are provided for the solepurpose of illustrating the operational principles of prior art and thatthey do not constitute any admission as to prior disclosure of specificconfigurations of the apparatus. These figures show how the feed switchopening 7 is closed by a valve portion 11.

As shown, each of the interconnecting portions 62 of a sealing member 60has an engaging portion 64 disposed on the inner side. Each engagingportion 64 is received by a corresponding recessed portion 76 disposedon the outer peripheral side of the valve portion 11.

A sealing gap E is provided between each engaging portion 64 and aninner face portion 77 of the corresponding recessed portion 76. Theinner face portion 77 is located on the side opposite from the otherside where the feed switch opening 7 of the intake manifold 1 islocated, relative to the engaging portion 64, when the feed switchportion 7 is closed by the valve portion 11.

In general, the valve portions 11 and the sealing members 60 are formedby resin molding. Therefore, if the sealing gap E is small, a engagingportion 64 may come into contact with the corresponding inner faceportion 77 of the recessed portion 76 due to manufacturing variations inthe valve portions 11 and the sealing members 60. When this happens, theinterconnecting portion 62 will be pressed against a bore portion 8,which results in an increase in resistance in the switching operation ofthe valve portion 11. Therefore, the sealing gap E is configured so asto avoid such contact between the engaging portions 64 and the innerface portions 77, regardless of the manufacturing variations in thevalve portions 11 and the sealing members 60.

For this reason, the sealing gap E was conventionally set larger than avalve gap C provided between the outer peripheral edge 15 a of eachvalve portion 11 and the bore portion 8.

In addition, the inner surface of the bore portion 8 and the outerperipheral edge 15 a were conventionally arc-shaped and coaxial withtheir center at the rotational center P of the valve portions 11. Aresult was a problem illustrated in FIG. 14( b).

Specifically, when the rotary valve is switched to the closed positionso that the valve portions 11 close the feed switch openings 7, therotary valve starts to vibrate due to e.g. pulsation of intake airgenerated in the air feeding passages caused by operation of theinternal combustion engine. As a result, the rotary valve will bedeformed such that the valve portions 11 are repeatedly displaced towardand away from the respective feed switch openings 7. The displacement ofa valve portion 11 toward the corresponding feed switch opening 7 causesmovement of the valve portion 11 relative to the sealing member 60,which leads eventually to collisions of the outer peripheral edge of thevalve portion 11 against the bore portion 8 in the vicinity of the feedswitch opening 7, thus casing a collision noise.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an intake apparatus foran internal combustion engine, which facilitates switching operation ofthe rotary valve and which can reduce generation of such collision noisedescribed above.

According to an aspect of the present invention, in an intake apparatusfor an internal combustion engine, the apparatus comprises an intakemanifold including a plurality of air feeding passages that define feedswitch openings and a bore portion and that are adapted to be connectedto and feed air to a plurality of cylinders of an internal combustionengine when the air feeding passages are connected to the internalcombustion engine;

a rotary valve defining an axial direction and including a plurality ofvalve portions that are rotatable together about a rotational axis andeach of which is in communication with corresponding one of the airfeeding passages through corresponding one of the feed switch openings,the rotary valve located in the bore portion and being supported to theintake manifold to be rotatably switched between an open positionwherein the plurality of valve portions open the feed switch opening anda closed position wherein the plurality of valve portions close the feedswitch openings, each of the valve portions including a closing areaportion for closing the corresponding feed switch opening and an openarea portion for opening the corresponding feed switch opening wherein afirst distance from a first central portion, with respect to aperipheral direction of the valve portions, of an outer peripheral edgeof the closed area portion to the rotational axis is set smaller than asecond distance from a second central portion, with respect to theperipheral direction, of an outer peripheral edge of the open areaportion to the rotational axis;

a sealing member fitted to each of the valve portions, the sealingmember including a pair of ring portions, each of which engagescorresponding one of opposite ends of the valve portion in the axialdirection and at least two interconnecting portions interconnecting thepair of ring portions, each of the sealing members providing sealingbetween associated one of valve portions and the bore portion of theintake manifold, the interconnecting portions being generally locatedalong the feed switch opening and radially between the valve portion andthe bore portion when the rotary valve is switched to the closedposition; and

a pair of recessed portions defined on an outer side of each of thevalve portions for receiving engaging portions defined on inner sides ofthe interconnecting portions of each of the sealing members.

With the arrangement described above, when the closed area portion is toclose the corresponding switch feed opening, the closed area portion canbe located farther from the feeding switching opening in comparison withthe open area portion for opening the feeding switching opening. Thus,it is more difficult for the valve portion to collide with the boreportion in the event that the valve portion is displaced toward thefeeding switching opening. Further, when the open area portion opens thefeeding switching opening, because of the smaller gap between the valveportion and the bore portion in the vicinity of the feed switch opening,there would be less air turbulence in the vicinity of the feed switchopening. Consequently, this arrangement allows an intake apparatus tohave improved performance where air is supplied to the internalcombustion engine more quietly and with stability.

According to an aspect of the present invention, the outer peripheraledge of the open area portion of the valve portion is formed as anarc-shaped edge centered at the rotational axis.

Thus, the open area portion can be aligned with the feed switch openingwith better precision, so that the air turbulence in the vicinity of thefeeding switching opening can be reduced even more effectively.Consequently, an intake apparatus with this arrangement can supply airto the internal combustion engine more quietly.

According to an aspect of the present invention, the valve portionincludes a reinforcing area portion disposed on a side opposite from theclosed area portion relative to the valve rotational axis, and a thirddistance from a third central portion, with respect to the peripheraldirection, of an outer peripheral edge of the reinforcing area portionto the rotational axis is set smaller than the second distance.

Thus, the valve portion can be reinforced in a way that makes it easy tobalance weights of the reinforcing area portion and the closed areaportion. As a result, the stiffness of the valve portion can be improvedand thus reducing deformation of the rotary valve. Furthermore, therotational balance of the rotary valve can be improved, thusfacilitating rotation and switching of the rotary valve. Further, athird distance from a third central portion, with respect to theperipheral direction, of an outer peripheral edge of the reinforcingarea portion to the rotational axis is set smaller than the seconddistance which is from a second central portion, with respect to theperipheral direction, of an outer peripheral edge of the open areaportion to the rotational axis. This arrangement makes it possible toeffectively prevent generation of collision noise between thereinforcing area portion of the valve portion and the bore portionresulting from the deformation of the rotary valve.

According to an aspect of the present invention, when the rotary valveis switched to the closed position, a sealing gap between the ladderengaging portion and an inner face portion of the recessed portionlocated, with respect to the ladder engaging portion, on the sideopposite from the side where the feed switch opening is present issmaller than a valve gap provided between the valve portion and the boreportion, and the first distance is set greater than the third distance.

Thus, even when the valve portion is deformed toward the feed switchopening, if this deformation reaches the amount of the sealing gap, theinner face portion comes into contact with the engaging portion, wherebythe interconnecting portions prevent further movement of the valveportion, thereby making it more difficult to have further displacementof the valve portion toward the bore portion. The first distance from afirst central portion, with respect to a peripheral direction of thevalve portions, of an outer peripheral edge of the closed area portionto the rotational axis is set greater than the third distance from athird central portion, with respect to the peripheral direction, of anouter peripheral edge of the reinforcing area portion to the rotationalaxis. This allows a sufficient distance between central portion of theouter peripheral edge of the reinforcing portion and the bore portion,which helps reducing collision noise between the valve portion and thebore portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of the presentinvention will become more apparent from the following detaileddescription considered with reference to the accompanying drawings,wherein:

FIG. 1 is a vertical sectional view of an intake apparatus for aninternal combustion engine;

FIG. 2 is a sectional view showing a closed condition of short ports;

FIG. 3 is a sectional view taken along III-III in FIG. 1;

FIG. 4 is a sectional view showing an open condition of the short ports;

FIG. 5 is a sectional view showing a closed condition or a closedposition of a valve portion;

FIG. 6 is a sectional view showing a ladder engaging portion and aladder receiving recessed portion;

FIG. 7 is a sectional view showing a displaced condition of the valveportion;

FIG. 8 is an overall perspective view of the rotary valve and a sealingmember;

FIG. 9 is a front view of the rotary valve;

FIG. 10 is a sectional view taken along X-X in FIG. 9;

FIG. 11 is a sectional view taken along XI-XI in FIG. 9;

FIG. 12 is a sectional side view of the valve portion;

FIG. 13 is a sectional side view of valve portions of a rotary valveaccording to the second embodiment;

FIG. 14( a) is a sectional view showing a closed condition or positionof a conventional valve portion;

FIG. 14( b) is a sectional view showing a displaced condition of theconventional valve portion.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be described withreference to the accompanying drawings. In the following description, aterm “portion”, if not explicitly specified, may be an integral part ofa member or may be formed as a separate part. When something is said tobe “defined” by an object, if not explicitly specified, it may beactually defined by the object or may be defined by a separate partwhich may be considered to be a part of the object.

First Embodiment

FIG. 1 is a vertical sectional view showing an intake apparatus for aninternal combustion engine in accordance with an embodiment of thepresent invention. FIG. 3 is a sectional view taken at III-III inFIG. 1. As shown in these figures, the intake apparatus for an internalcombustion engine in accordance with the embodiment of the inventionincludes an intake manifold 1 and a rotary valve 10 incorporated withinthis intake manifold 1 and the apparatus is mounted to a four-cylindertype internal combustion engine 2.

The intake manifold 1 includes four intake pipe-like or tubular members1 a connected in series and integrally formed with each other, withthese four intake pipe-like members 1 a forming four air feedingpassages or conduits 3 connected respectively to the four cylinders ofthe internal combustion engine 2. As shown in FIG. 1, the intakemanifold 1 further includes a surge tank 4 connected to the four intakepipe-like members 1 a. Each air feeding passage 3 includes a long port 5having an inlet opening 5 a that opens to the surge tank 4 and a shortport 6 having an inlet opening 6 a that opens to the surge tank 4. Thefour intake pipe-like members 1 a and the surge tank 4 of the intakemanifold 1 are formed by resin molding.

The rotary valve 10 is supported to a pair of axial bearing portions 1 bof the intake manifold 1 with the rotary valve 10 being inserted intoand through a bore portion 8 having feed switch openings 7 for therespective short ports 6. Further, this rotary valve 10 is rotatablydriven about an axis P by means of an actuator 9 having an output shaft9 a operatively coupled with a support shaft 13 provided at one extremeend of this rotary valve 10, so that the rotary valve 10 is switchedbetween a closed condition or a closed position where each feed switchopening 7 of the respective short port 6 is closed and an open conditionor a closed position where each feed switch opening 7 of the respectiveshort port 6 is closed.

When the internal combustion engine 2 rotates at a low speed, the rotaryvalve 10 is switched to the closed condition or closed position to closeeach short port 6 so that it is no longer communicated with the surgetank 4, which switches each air feeding passage 3 to an air feeding modefor low speed (or a low speed air feeding mode). As a result, each airfeeding passage 3 feeds air, which is introduced into the surge tank 4from a throttle (not shown), to the cylinders as combustion air throughthe long port 5 by the suction action of the cylinders. When theinternal combustion engine 2 rotates at a high speed, the rotary valve10 is switched to the open condition or the open position to open eachshort port 6 to be in communication with the surge tank 4, whichswitches each air feeding passage 3 to an air feeding mode for highspeed (or a high speed air feeding mode). As a result, each air feedingpassage 3 feeds air, which is introduced to the surge tank 4, to thecylinders as combustion air through the short port 6 by the suctionaction of the cylinders. In case of the high-speed air feeding mode, thelong port 5 in each air feeding passage is also communicated with thesurge tank 4.

Next, the rotary valve 10 will be described in greater details. FIG. 3shows a vertical section of the rotary valve 10. FIG. 8 is a perspectiveview showing the entire rotary valve 10. FIG. 9 is a front view showingthe entire rotary valve 10. FIG. 10 is a sectional view taken along X-Xin FIG. 9. FIG. 11 is a sectional view taken along XI-XI in FIG. 9.

As shown in these figures, the rotary valve 10 includes four valveportions 11 juxtaposed coaxially along the direction of the rotary axisP of this rotary valve 10 and the support shafts 12, 13 provided at theopposed ends of the rotary valve 10 to be rotatably supported to theaxial bearing portions 1 b of the intake manifold 1. The four valveportions 11 are formed by resin molding. Further, the four valveportions 11 are interconnected by a plurality of connecting members 14formed by resin molding simultaneously and integral with the valvemembers 11 and juxtaposed along the peripheral direction of the valveportions 11 between respective adjacent valve portions 11, so that thevalve portions 11 are rotatable together. The one support shaft 12 is ametal support shaft having one end thereof rotatably embedded in theextreme end of the rotary valve 10. This support shaft 12 is rotatablysupported in a support hole formed in the axial bearing portion 1 b viaa resin bearing 18 and an O-ring 19 for axial alignment. The supporthole of the axial bearing portion 1 b is formed as a recessed portionconfigured to prevent air leak to the outside of the intake manifold.The other support shaft 13 is formed integrally with the extreme end ofthe rotary valve 10 by resin molding. This support shaft 13 is supportedto the axial bearing portion 1 b via the output shaft 9 a of theactuator 9. The four valve portions 11 correspond respectively to thefour short ports 6 and open and close the feed switch openings 7. Therotary valve 10 includes a plurality of side plate portions 15 disposedside by side and spaced apart along the direction of its rotational axisP. And, the rotary valve 10 is tapered with the side wall portion 15disposed adjacent one end where the one support shaft 12 is present hasan outer diameter slightly smaller than an outer diameter of the sidewall portion 15 disposed at the other end where the other support shaft13 is present.

Each valve portion 11 includes a closed area portion 20 having a bottomplate member 21, a reinforcing area portion 30 disposed on the oppositeside from the closed area portion 20 with respect to the rotational axisP which is the rotational axis of the valve portion 11, an open areaportion 40 disposed between and defined by the reinforcing area portion30 and the closed area portion 20 and having a port hole 41, and acommunicating area portion 50 disposed on the opposite side from theopen area portion 40 with respect to the rotational axis P of the valveportion 11 and having a communication hole 51. The communicating areaportion 50 is preferably in unobstructed or uninterrupted communicationwith the open area portion 40. Each bottom plate member 21 may have aflat surface that faces and defines a part of the open area portion 40and communicating area portion 50.

The closed area portion 20 is defined by a pair of side plate portions15 disposed at the opposed ends of the valve portion 11, the bottomplate member 21 formed continuously with the pair of the side plateportions 15, and a pair of wall plate members 22 disposed at opposedends in the peripheral direction of the valve portion on the outwardfacing surface of the bottom plate member 21 such that the wall platemembers 22 extend away from and preferably perpendicular to the bottomplate member 21. This closed area portion 20 includes a recessed portion23 (FIG. 10) defined between the wall plate members 22 on the outer faceside of the bottom plate member 21 and a plurality of reinforcing ribs24 provided within the recessed portion 23 and on the outer face side ofthe bottom plate member 21 such that reinforcing ribs 24 extend awayfrom and preferably perpendicular to the bottom plate member 21.

The reinforcing area portion 30 is defined by the pair of side plateportions 15, and a reinforcing plate member 31 formed continuously withan adjacent pair of side plate portions 15. And, this reinforcing areaportion 30 includes a plurality of reinforcing ribs 32 juxtaposed on theouter face side of the reinforcing plate 31 such that the reinforcingribs 32 are spaced apart in the peripheral direction of the valveportion 11.

The open area portion 40 includes one radial end portion of acylindrical member 42 defined by the pair of side plate portions 15, thebottom plate member 21, and the reinforcing plate member 31, and theport 41 which is an opening provided at one radial end portion of thecylindrical member 42. The communicating area portion 50 includes aradial end portion on the opposite side of the cylindrical member 42 andthe communication hole 51 which is an opening provided at the radiallyopposite end portion of the cylindrical member 42. The port 41 and thecommunication hole 51 are communicated with each other via thecylindrical member 42.

FIG. 12 is a sectional side view of each bore portion 8. A solid line(a) in this figure denotes the inner peripheral face of the bore portion8. As shown in this figure, the bore portion 8 has an inner face whichis circular with its center at the rotational axis P of the valveportion 11 as seen in the direction along this rotational axis P. On theother hand, the valve portion 11 has an outer peripheral shape withdifferent distances D1, D3, D2 from the rotational axis P to outerperipheral edges 20 a, 30 a, and 40 a of the closed area portion 20, thereinforcing area portion 30 and the open area portion 40 respectively.

More particularly, the distance D1 is a distance from the rotationalaxis P to a center portion 25 (or a central point), with respect to theperipheral direction of the valve portion, of the outer peripheral edge20 a of the closed area portion 20. The distance D2 is a distance fromthe rotational axis P to a center portion 43 (or a central point), withrespect to the peripheral direction of the valve portion, of the outerperipheral edge 40 a of the open area portion 40. The distance D3 is adistance from the rotational axis P to a center portion 33 (or a centralpoint), with respect to the peripheral direction of the valve portion,of the outer peripheral edge 30 a of the reinforcing area portion 30.And, the outer peripheral shape of the valve portion 11 is formed suchthat D2 is greater than D1 and that D1 is greater than D3 among thedistance D1 for the closed area portion 20, the distance D2 for the openarea portion 40 and the distance D3 for the reinforcing area portion 30.Further, a distance D4 is a distance from the rotational axis P to acenter portion 52, with respect to the peripheral direction of the valveportion, of an outer peripheral edge 50 a of the communicating areaportion 50. And, this distance D4 is set to be the same as the distanceD2 for the open area portion 40.

The outer peripheral edges 40 a, 50 a of the open area portion 40 andthe communicating area portion 50 are formed as arc-shaped outerperipheral edges centered at the rotational axis P. The outer peripheraledge 20 a of the closed area portion 20 has its center 26 at a positionaway from the rotational axis P toward the side where the reinforcingarea portion 30 is present and is formed as an arc-shaped outerperipheral edge having the same radius R as the inner peripheral face ofthe bore portion 8. The outer peripheral edge 30 a of the reinforcingarea portion 30 has its center 34 at a position away from the rotationalaxis P toward the side where the closed area portion 20 is present andis formed as an arc-shaped outer peripheral edge having the same radiusR as the inner peripheral face of the bore portion 8.

As shown in FIG. 3, the rotary valve 10 includes a sealing member 60attached to each valve portion 11. FIG. 8 is a perspective view showingthe sealing member 60 in its entirety. As shown in this figure, thesealing member 60 has a pair of circular ring portions 61 and a pair ofinterconnecting portions 62 interconnecting the pair of ring portions61. The interconnecting portions 62 will be referred to as ladderportions 62. However, while an exemplary structure of the ladderportions will be described below, the term ladder per se is not limitingas to their shapes. The pair of ring portions 61, 61 and the pair ofladder portions 62 are formed integrally by resin molding. Each ringportion 61 has an opening or a cut out 63 disposed on a radiallyopposite side from the side where the pair of ladder portions 62 arepresent, with respect to the center of this ring portion 61. Each ladderportion 62 has an outer peripheral face or edge 62 a which is formed asan arcuate face which is preferably substantially circular except forthe opening or the cut out 63 as viewed along the direction of therotational axis P of the valve portion 11. The outer diameter of thesealing member 60 at each ladder portion 62, that is, a distance betweenan outer surface of each ladder portion 62 and the center of the ringportion 61 is set slightly smaller than the outer diameter thereof ateach ring portion 61.

The sealing member 60 of each valve portion 11 is attached to the valveportion 11 by the following attaching arrangement. This attachingarrangement is shown in FIGS. 3 through 11.

As shown in these figures, a ring support portion 70 is provided on eachaxially outer side of the side plate portion 15 at each opposite end ofthe valve portion 11. Each ring support portion 70 disposed betweenadjacent valve portions 11 is defined by the side plate portion 15, eachconnecting member 14 and a pin member 71 formed continuously with theassociated connecting member 14. This ring support portion 70 isprovided in the form of an annular groove including a groove bottomdefined by end faces of each connecting member 14 and side walls definedby the side plate portion 15 and the pin member 71. The ring supportportion 70 included in each of the valve portions 11 disposed at theopposite ends of the rotary valve 1 on the side thereof opposite fromthe adjacent valve portion 11 is defined by the side plate portion 15and a plurality of support members 16 distributed on the axially outerface side of this side plate portion 15 along the peripheral directionof the valve portion 11. This ring support portion 70 is provided in theform of an annular groove including a groove bottom defined by the sideplate of each support member 16 and a side wall defined by the sideplate portion 15.

FIGS. 3, 5 and 11 illustrate the valve portions 11 with the respectivesealing members 60 attached or fitted. In FIG. 11, the ring portion 61is shown with dotted lines. As shown in these figures, each of the pairof ring portions 61 is fitted to, or engages and rests on correspondingone of the pair of ring support portions 70, 70 from radially outside.Each ring portion 61 is elastically deformed to have a reduced diameterby a force applied thereto due to its contact with the bore portion 8.The deformation is allowed by the opening or the cut out 63. The ringportion 61 engages, mounted to, or fits onto the ring support portion 70from radially outside under this elastically deformed condition. As aresult, an outer peripheral face 61 a of each ring portion 61 is pressedagainst the inner face of the bore portion 8. To fit the ring portion 61onto the ring support portion 70, the ring portion 61 is elasticallydeformed to increase the diameter and to enlarge the opening 63, so thatthe ring member 61 may engage the ring support portion 70 from radicallyoutside through the enlarged opening 63.

As shown in FIG. 5, each ladder portion 62 includes, on the inner sideof the sealing member, a ladder engaging portion 64 (or an engagingportion) extending along the entire length of the ladder portion 62.This ladder engaging portion 64 includes a ridge or an elongateprojection 64 a extending along the entire length of the ladder portion62. The ridges or the elongate projections 64 a of the pair of ladderportions 62 project toward each other in an axial view. On the otherhand, as best seen in FIG. 6, the valve portion 11 includes a pair ofladder support portions 75 disposed on the outward sides of the closedarea portion 20 in the valve rotational direction. Each ladder supportportion 75 is defined by an end portion 21 a of the bottom plate member21 and the wall plate member 22. In the valve portion outer face side ofeach ladder support portion 75, there is provided a ladder receivingrecessed portion 76 (or a recessed portion). Each of the pair of ladderengaging portions 64 is engaged and received in the respective one ofthe pair of ladder receiving recessed portions 76.

FIG. 4 is a sectional view showing each short port 6 and each valveportion 11 when the rotary valve 10 is switched to the open condition orthe open position.

As shown in this figure, when the rotary valve 10 is switched to theopen condition or the open position, the open area portion 40 of thevalve portion 11 faces the feed switch opening 7, thus opening the feedswitch opening 7 through the port 41. At this time, the communicationhole 51 of the communicating area portion 50 faces the inlet opening 6 aof the short port 6 and the feed switch opening 7 is in communicationwith the inlet opening 6 a. At this time, the outer peripheral faces ofthe two ring portions 61 of the sealing member 60 project radiallybeyond the outer peripheral edge of the open area portion 40 to theouter periphery side of the open area portion 40 so as to be in contactwith the inner peripheral faces of the bore portion 8 at positions alongend regions of the feed switch opening 7 in the rotational axisdirection of the valve portion 11 due to the elastic force from the ringportion 61. As a result, the ring portions 61 seal the gaps between thevalve portion 11 and the bore portion 8 on the both end sides of thefeed switch opening 7 in the direction of the rotational axis of thevalve portion, thereby reducing turbulence, in the vicinity of the feedswitch opening 7, in the air fed to the internal combustion engine 2through the short port 6. Further, under this condition, in the valveportion 11, a valve gap B2 is formed between the center 43 of the outerperipheral edge 40 a of the opening area portion 40 and the innerperipheral face of the bore portion 8.

FIGS. 2 and 5 are sectional views showing each short port 6 and eachvalve portion 11 when the rotary valve 10 is switched to the closedcondition or the closed position.

As shown in these figures, when the rotary valve 10 is switched to theclosed condition or the closed position, the closed area portion 20 ofthe valve portion 11 faces the feed switch opening 7, thus closing thefeed switch opening 7 with the side plate portion 15, the wall platemember 22 and the bottom plate member 21. At this time, the outerperipheral faces of the two ring portions 61 of the sealing member 60project radially beyond the outer peripheral edge 20 a of the closedarea portion 20 to the outer periphery side of the closed area portion20 so as to be in contact with the inner peripheral faces of the boreportion 8 at positions along end regions of the feed switch opening 7 inthe rotational axis direction of the valve portion 11 due to the elasticresilience force from the ring portion 61. On the other hand, the pairof ladder portions 62, 62 are disposed on the opposite sides of the feedswitch opening 7 with respect to the peripheral direction of the valveportion 11 and disposed between the valve portion 11 and the boreportion 8 at positions on one side of the feed switch opening 7 in theperipheral direction of the valve portion 11. As a result, the ringportions 61 seal the gaps between the valve portion 11 and the boreportion 8 on both end sides of the feed switch opening 7 in thedirection of the rotational axis of the valve portion 11 and the ladderportions 62 seal the gaps between the valve portion 11 and the boreportion 8 on both end sides of the feed switch opening 7 in theperipheral direction of the valve portion 11. However, the outerperipheral face 62 a of each ladder portion 62 is slightly recededtoward the inner side of the valve portion 11 than the outer peripheralface 61 a of the ring portion 61, thus is not in contact with the innerperipheral face of the bore portion 8.

FIGS. 5 and 6 show how each ladder engaging portion 64 engages with theladder receiving recessed portion 76 when the rotary valve 10 isswitched to the closed condition or the closed position.

As shown in these figures, the inner faces of the ladder receivingrecessed portion 76 includes a first inner face portion 77 that isdisposed on the side opposite from the side where the feed switchopening 7 is present relative to the ladder engaging portion 64 when thefeed switch opening 7 is closed by the valve portion 11. That is, thefirst inner face portion 77 faces the ladder engaging portion 64. Afirst sealing gap A is provided between the first inner face portion 77and a portion of the ladder engaging portion 64 facing the first innerface portion 77. The first sealing gap A is provided along the entirelength of the first inner face portion 77 along the direction of therotational axis of the valve portion 11. On the other hand, the valveportion 11 is constructed such that a valve gap B1 is present betweenthe center portion 25 of the outer peripheral edge 20 a of the closedarea portion 20 and the inner peripheral face of the bore portion 8.This valve gap B1 is greater than the gap B2 when the feed switchopening 7 is opened by the open area portion 40. With the rotary valve10 in its closed condition or the closed position, the first sealing gapA is smaller than the valve gap B1.

When the rotary valve 10 is switched to the closed condition or theclosed position, an end 75 a of one ladder support portion 75 comes intocontact with an end face 62 b of the ladder portion 62 of the sealingmember 60, whereby the sealing member 60 is rotated together with thevalve portion 11.

When the valve portion 11 closes the feed switch opening 7, due to e.g.pulsation in the introduced air in the respective air feed passages 3caused by operation of the internal combustion engine 2, a vibrationsdevelop about the portions at opposite ends of the rotary valve 10supported by the support shafts 12, 13. This causes the valve portion 11and the sealing member 60 to move relative to each other within thegrooves of the ring support portions 70 and inside the ladder receivingrecessed portion 76. This causes deformation in the rotary valve 10wherein each valve portion 11 repeatedly moves toward and away from thefeed switch opening 7. FIG. 7 shows the valve portion 11 that isdisplaced toward the feed switch opening 7. Since the valve gap B1before the displacement of the valve portion 10 is greater than thevalve gap B2 with the feed switch opening opened by the open areaportion 40, the closed area portion 20 does not collide with the boreportion 8 regardless of the displacement of the valve portion 11.Further when the displacement of the valve portion 11 reaches thesealing gap A, the first inner face portion 77 of the ladder receivingrecessed portion 76 comes into contact with the ladder engaging portion64. Since the outer peripheral face 61 a of each ring portion 61 of thesealing member 60 is in contact with the corresponding inner peripheralface of the bore portion 8, the ladder portions 62 function as stoppersagainst further displacement of the first inner face portion 77, thuslimiting further displacement of the valve portion 11. Since the sealinggap A prior to the deformation of the valve portion 11 is smaller thanthe valve gap B1, collisions between the closed area portion 20 of thevalve portion 11 and the bore portion 8 are further reduced in spite ofthe displacement of the valve portion 11.

Second Embodiment

FIG. 13 is a sectional side view of a bore portion 8 of an intakeapparatus for an internal combustion engine according to the secondembodiment. A solid line (a) in this figure denotes the inner peripheralface of the bore portion 8.

As shown in this figure, the bore portion 8 has a circular inner facethat is centered at the rotational axis P of the valve portion 11 asseen in the direction along this rotational axis P. On the other hand,the valve portion 11 has an outer peripheral shape with differentdistances D1 a, D3 a, D2 from the rotational axis P to outer peripheraledges 20 a, 30 a, 40 a respectively of the closed area portion 20, thereinforcing area portion 30 and the open area portion 40.

More specifically, the distance D1 a is a distance from the rotationalaxis P to a center portion 25 (or a central point), with respect to theperipheral direction of the valve portion, of the outer peripheral edge20 a of the closed area portion 20. The distance D2 is a distance fromthe rotational axis P to a center portion 43 (or a central point), withrespect to the peripheral direction of the valve portion, of the outerperipheral edge 40 a of the open area portion 40. The distance D3 a is adistance from the rotational axis P to a center portion 33 (or a centralpoint), with respect to the peripheral direction of the valve portion,of the outer peripheral edge 30 a of the reinforcing area portion 30.The outer peripheral shape of the valve portion 11 is such that D2 isgreater than D1 a, and that D1 a is greater than D3 a among the distanceD1 a for the closed area portion 20, the distance D2 for the open areaportion 40 and the distance D3 a for the reinforcing area portion 30.Further, a distance D4 is a distance from the rotational axis P to acenter portion 52, with respect to the peripheral direction of the valveportion, of an outer peripheral edge 50 a of the communicating areaportion 50. This distance D4 is set to be the same as the distance D2for the open area portion 40.

The outer peripheral edges 40 a, 50 a of the open area portion 40 andthe communicating area portion 50 are formed as arc-shaped outerperipheral edges centered at the rotational axis P. The outer peripheraledge 20 a of the closed area portion 20 has outer peripheral edgesformed by taking an arc centered about the rotational axis P and havingthe same radius as the radius of the outer peripheral edge 40 a of theopen area portion 40 and by drawing three straight chords each ending attwo of adjacent points out of four points (including the two points 25a) positioned over the arc and by removing regions between the arc andthe chords. The distance D1 b from the rotational axis P to the outerperipheral edge 20 a of the open area portion 20 at two points 25 a, 25a thereof is greater than the distance D1 a described above. The outerperipheral edge 30 a of the reinforcing area portion 30 has outerperipheral edges formed by taking an arc centered at the rotational axisP and having the same radius as the radius of the outer peripheral edge40 a of the open area portion 40 and by drawing three straight chordseach ending at two of adjacent points out of four points (including thetwo points 33 a) positioned over the arc and by removing regions betweenthe arc and the chords. The distance D3 b from the rotational axis P tothe outer peripheral edge 30 a of the reinforcing area portion 30 at twopoints 33 a, 33 a thereof is greater than the distance D3 a describedabove.

Other Embodiment

In the foregoing respective embodiments, the distance from therotational axis P to the center 33 of the reinforcing area portion 30 isset smaller than the distances from the rotational axis P to the centers25, 43 of the closed area portion 20 and the open area portion 40.Alternatively, it is also possible to employ an alternative arrangementin which the distance from the rotational axis P to the center 33 of thereinforcing area portion 30 is equal to the distance from the rotationalaxis P to the center 25 of the closed area portion 20 or the distancefrom the rotational axis P to the center 43 of the open area portion 40,which also achieves an object of the invention.

Specific shapes of the outer peripheral edges 20 a and 30 a are notlimited to the ones described above and illustrated in the drawings. Aperson skilled in the art will understand that the relationships in thedistances as defined in the claims are achievable with other shapes.

There may be more than two ladder or interconnecting portions. A personskilled in the art will be able to choose appropriate locations foradditional interconnecting portion(s).

1. An intake apparatus for an internal combustion engine, the apparatuscomprising: an intake manifold (1) including a plurality of air feedingpassages (3) that define feed switch openings (7) and a bore portion (8)and that are adapted to be connected to and feed air to a plurality ofcylinders of an internal combustion engine when the air feeding passages(3) are connected to the internal combustion engine; a rotary valve (10)defining an axial direction and including a plurality of valve portions(11) that are rotatable together about a rotational axis (P) and each ofwhich is in communication with corresponding one of the air feedingpassages (3) through corresponding one of the feed switch openings (7),the rotary valve (10) located in the bore portion and being supported tothe intake manifold (1) to be rotatably switched between an openposition wherein the plurality of valve portions (11) open the feedswitch openings (7) and a closed position wherein the plurality of valveportions (11) close the feed switch openings (7), each of the valveportions (11) including a closing area portion (20) for closing thecorresponding feed switch opening (7) and an open area portion (40) foropening the corresponding feed switch opening (7) wherein a firstdistance (D1) from a first central portion (25), with respect to aperipheral direction of the valve portions (11), of an outer peripheraledge (20 a) of the closed area portion (20) to the rotational axis (P)is set smaller than a second distance (D2) from a second central portion(43), with respect to the peripheral direction, of an outer peripheraledge (40 a) of the open area portion (40) to the rotational axis (P); asealing member (60) fitted to each of the valve portions (11), thesealing member (60) including a pair of ring portions (61), each ofwhich engages corresponding one of opposite ends of the valve portion(11) in the axial direction and at least two interconnecting portionsinterconnecting the pair of ring portions (61), each of the sealingmembers (60) providing sealing between associated one of valve portions(11) and the bore portion (8) of the intake manifold (1), theinterconnecting portions (62) being generally located along the feedswitch opening (7) and radially between the valve portion (11) and thebore portion (8) when the rotary valve (10) is switched to the closedposition; and a pair of recessed portions (76) defined on an outer sideof each of the valve portions (11) for receiving engaging portions (64)defined on inner sides of the interconnecting portions of each of thesealing members (60).
 2. The intake apparatus for an internal combustionengine, according to claim 1, wherein the outer peripheral edge (20 a)of the open area portion (20) of the valve portion (11) is formed as anarc-shaped edge centered at the rotational axis (P).
 3. The intakeapparatus for an internal combustion engine, according to claim 2,wherein the valve portion (11) includes a reinforcing area portion (30)disposed on a side opposite from the closed area portion (20) relativeto the valve rotational axis (P): and a third distance (D3 a) from athird central portion (33), with respect to the peripheral direction, ofan outer peripheral edge (30 a) of the reinforcing area portion (30) tothe rotational axis (P) is set smaller than the second distance (D2). 4.The intake apparatus for an internal combustion engine, according toclaim 3, wherein; when the rotary valve (10) is switched to the closedposition, a sealing gap (A) between the ladder engaging portion (62) andan inner face portion (77) of the recessed portion (76) located, withrespect to the ladder engaging portion (62), on the side opposite fromthe side where the feed switch opening (7) is present is smaller than avalve gap (B1) provided between the valve portion (11) and the boreportion (8); and the first distance (D1 a) is set greater than the thirddistance (D3 a).
 5. The intake apparatus for an internal combustionengine, according to claim 1, wherein the valve portion (11) includes areinforcing area portion (30) disposed on a side opposite from theclosed area portion (20) relative to the valve rotational axis (P): anda third distance (D3 a) from a third central portion (33), with respectto the peripheral direction, of an outer peripheral edge (30 a) of thereinforcing area portion (30) to the rotational axis (P) is set smallerthan the second distance (D2).
 6. The intake apparatus for an internalcombustion engine, according to claim 5, wherein; when the rotary valve(10) is switched to the closed position, a sealing gap (A) between theladder engaging portion (62) and an inner face portion (77) of therecessed portion (76) located, with respect to the ladder engagingportion (62), on the side opposite from the side where the feed switchopening (7) is present is smaller than a valve gap (B1) provided betweenthe valve portion (11) and the bore portion (8); and the first distance(D1 a) is set greater than the third distance (D3 a).